Use of abscisic acid on ornamental plants

ABSTRACT

The present invention describes a method for increasing the drought tolerance of selected ornamental plants comprising administering abscisic acid (ABA) or its salts to said plants.

FIELD OF THE INVENTION

The present invention relates to a method of delaying the wilting ofdrought stressed ornamental plants.

BACKGROUND OF THE INVENTION

Abscisic acid (ABA) is a natural occurring hormone found in all higherplants (Cutler and Krochko. 1999. Trends in Plant Science. 4: 472-478.;Finkelstein and Rock. 2002. The Arabidopsis Book. ASPB, Monona, Md.,1-52). ABA is involved in many major events of plant growth anddevelopment including dormancy, germination, bud break, flowering, fruitset, growth and development, stress tolerance, ripening, abscission andsenescence. One of the roles of ABA is the regulation of water relationsin plants through the control of stomata opening and closure.

Most plants have improved drought tolerance following application ofABA, but plants differ in their sensitivity to applied ABA. Differenttypes of ornamental plants differ in both the extent of increaseddrought tolerance and potential for undesirable side effects from ABAtreatment. Others have reported ABA effects on transpiration of wholeplants or excised plant parts and yellowing of excised plant parts.Foliar application of ABA reduced the transpiration of potted Poinsettiaplants (Krizek, et al., 1986, Influence of soil moisture and ABA acidpretreatment in modifying SO₂ sensitivity in poinsettia, J. Amer. Hort.Sci. 111:446-450). ABA applied through the petiole of excised Coleusleaves reduces their transpiration rate compared to excised leavesstanding in water (Rajapakse, et al., 1988, Transpiration and water useof potted floricultural plants under low light conditions, J. Amer.Hort. Sci. 113:910-914). Treatment of Geranium cuttings causes theundesirable effect of leaf yellowing (Mutui et al., 2005, Journal ofHorticultural Science & Biotechnology 80: 453-550). There are noprevious reports that could be used to determine which ornamental plantsbenefit from ABA application in terms of reduced transpiration rateswithout unacceptable risk of ABA-induced leaf yellowing or abscission.

SUMMARY OF THE INVENTION

The present invention is directed to the treatment of an ornamentalplant selected from the group consisting of Celosia, Chrysanthemum,Coleus, Cosmos, Cuphea, Dianthus, Euryops, Hydrangea, Impatiens,Lantana, Marigold, New Guinea Impatiens, Pentas, Petunia, Salvia andSnapdragon to improve drought tolerance with only slight potential forundesirable side effects comprising applying an effective amount of ABAor a salt thereof to said plants.

DETAILED DESCRIPTION OF THE INVENTION

The applied concentration of ABA can vary widely depending on the watervolume applied to plants as well as other factors such as the plant ageand size, and plant sensitivity to ABA, but is generally in the range ofabout 1 ppm to about 10,000 ppm, preferably from about 10 to about 1000ppm.

It is also contemplated that salts of ABA may be utilized in accordancewith the present invention.

As used herein, the term “salt” refers to the water soluble salts ofABA. Representative such salts include inorganic salts such as theammonium, lithium, sodium, calcium, potassium and magnesium salts andorganic amine salts such as the triethanolamine, dimethylethanolamineand ethanolamine salts.

Other ingredients such as surfactants can be used in compositions usefulin the present invention.

The presently preferred surfactant for ABA performance is Brij 98(polyoxyethylene (20) oleyl ether) available from Uniqema (Castle,Del.). Other surfactants that are also useful in the present invention,including but not limited to other surfactants in the Brij family(polyoxyethylene fatty alcohol ether) from Uniqema (Castle, Del.);surfactants in the Tween family (Polyoxyethylene sorbitan esters) fromUniqema (Castle, Del.); Silwet family (Organosilicone) from UnionCarbide (Lisle, Ill.); Triton family (Octylphenol ethoxylate) from TheDow Chemical Company (Midland, Mich.); Tomadol family (ethoxylatedlinear alcohol) from Tomah3 Products, Inc. (Milton, Wis.); Myrj family(Polyoxyethylene (POE) fatty acid esters) from Uniqema (Castle, Del.);Span family (Sorbitan ester) from Uniqema (Castle, Del.); Trylox family(Ethoxylated Sorbitol and Ethoxylated Sorbitol Esters) from CognisCorporation (Cincinnati, Ohio). These surfactants, commerciallyavailable for agricultural use, are also useful in the presentinvention: Latron B-1956 (77.0% modified phthalic/glycerol alkyl resinand 23.0% Butyl alcohol) from Rohm & Haas (Philadelphia, Pa.); Caspil(Blend of Polyether-polymethylsiloxanecopolymer and nonionic surfactant)from Aquatrols (Paulsboro, N.J.); Agral 90 (Nonyl phenol ethoxylate)from Norac Concept. Inc. (Orleans, Ontario, Canada); Kinetic (99.00%proprietary blend of polyalkyleneoxide modified polydimethylsiloxane andnonionic surfactants) from Setre Chemical Company (Memphis, Tenn.); andRegulaid (90.6% 2-butoxyethanol, poloxalene, monopropylene glycol) fromKALO, Inc. (Overland Park, Kans.).

Many different commercial ornamental crops were obtained from localretailers, or from wholesale nurseries, and transported to a greenhousefor testing. Plants were watered to saturation and allowed to stand anddrain for about one hour. Plants were selected for uniformity based onleaf area and arranged in a randomized complete block design, or acompletely randomized design, on the greenhouse bench. The plants weresprayed or drenched with water or treatment solution equaling about5-10% of the pot volume. The plants were held without irrigation untilall the plants wilted to a point when they were determined to beunmarketable. The plants were rated daily for the extent of wilting on ascale from 1 for no wilting to 4 for complete wilting. A rating of 2.5was the point at which a plant was determined to be unmarketable and theprevious day was recorded as the marketable life of that plant in days.The plants were rated for the extent of lower leaf yellowing or leaf orflower abscission on a scale from 1 for no yellowing or abscission to 4for complete yellowing or abscission. A rating of 2.5 was the point atwhich a plant was determined to be unmarketable.

The present invention may be illustrated by the following representativeexample.

Example 1

Ornamental bedding plants were treated (sprayed or drenched) with wateror 250 ppm abscisic acid (S-ABA; ABA; S-(+)-abscisic acid; +-ABA,(+)-(S)-cis,trans-abscisic acid,(+)-(S)-cis,trans-ABA; S-ABA;(S)-5-(1-hydroxy-2,6,6,-trimethyl-4-oxo-2-cyclohexen-1-yl)-3-methyl-(2Z,4E)-pentadienoicacid; CAS no. 21293-29-8) and then irrigation was withheld until all theplants wilted. Plants were individually rated on a daily basis fordegree of wilting and other undesirable characteristics like leafyellowing.

In Table 1, plants were drenched with water or a 250 ppm ABA solution,and held in a greenhouse without irrigation.

TABLE 1 Classification of ornamental plants by ABA effects on droughttolerance and potential for undesirable side effects of lower leafyellowing or leaf or flower abscission. Leaf or Classifica- Market lifeLower leaf flower tion¹ Plant extension² yellowing³ abscision⁴ FavorableCelosia 2.3 1 1 Favorable Chrysanthemum 2.0 1 1 Favorable Coleus 2.3 1 1Favorable Cosmos 1.4 1 1 Favorable Cuphea 2.3 1 1 Favorable Dianthus 1.61 1 Favorable Euryops 3.3 1 1 Favorable Hydrangea 3.4 1 1 FavorableImpatiens 2.0 1 1 Favorable Lantana 2.4 1 1 Favorable Marigold 1.9 1 1Favorable New Guinea 3.3 1 1 Impatiens Favorable Pentas 2.8 1 1Favorable Petunia 3.5 1.9 1 Favorable Salvia 1.9 1 1 FavorableSnapdragon 1.5 1.3 1 Unfavorable Agapanthus 0 2 1 Unfavorable Alyssum 03.5 1 Unfavorable Calibrachoa 0 3 1 Unfavorable Gazania 0 3 1Unfavorable Lobelia 2.5 3 2.5 Unfavorable Pansy 1.6 3 1 UnfavorablePoinsettia 2.0 3 2.5 Unfavorable Rose 0 4 1 Unfavorable Vinca 2.5 2.5 3¹Classification: Favorable = increased market life due to delayedwilting without the occurrence of unmarketable lower leaf yellowing orabscission, Unfavorable = presence of unmarketable lower leaf yellowingor abscission. ²Market life extension = days of additional market lifecompared to control plants due to delayed wilting. ³Lower leaf yellowing= average rating where 1 = no yellowing, 2.5 = unmarketable due to lowerleaf yellowing, and 4 = severe lower leaf yellowing. ⁴Leaf or flowerabscission = average rating where 1 = no leaf or flower abscission, 2.5= unmarketable due to leaf or flower abscission, and 4 = severe leaf orflower abscission.

Many bedding plants like New Guinea Impatiens are very favorablecandidates for ABA application because treated plants have much greaterdrought tolerance without any noticeable undesirable side effects. Otherplants like Pansy are not favorable candidates for ABA applicationbecause even though the treated plants are more drought tolerant theundesirable effect of ABA-induced leaf yellowing often occurs. Otherplants like Vinca are not favorable candidates for ABA applicationbecause even though the treated plants are more drought tolerant theundesirable effect of flower abscission often occurs. Still other plantslike Calibrachoa are not favorable candidates because undesirable sideeffects like severe leaf yellowing occur before wilting symptoms developin the control and treated plants.

The invention claimed is:
 1. A method for extending the market life ofan ornamental plant selected from the group consisting of Impatiens, NewGuinea Impatiens and Pentas comprising applying from about 10 ppm toabout 1,000 ppm of abscisic acid or salts thereof to said plant byspraying or drenching, wherein said plant exhibits decreased wiltingwhile exhibiting low levels of leaf yellowing and/or leaf or flowerabscission.
 2. The method of claim 1 wherein the ornamental plant is NewGuinea Impatiens.
 3. The method of claim 1 wherein the ornamental plantis Impatiens.
 4. The method of claim 1 wherein the ornamental plant isPentas.